The development and commercialization of mobile communication equipment, including mobile radios and mobile telephones, have allowed communications between fixed base transmitters and receivers and mobile communication facilities installed in vehicles. As a result, the field of mobile communication has expanded substantially.
Mobile communication channels have been set aside in the 800-900 MHz range, as contrasted with the heretofore popular citizens band communications which operate in the 28-39 MHz range. Because of the higher operating frequencies of mobile communication transceivers, the antennas are much shorter in length and can be easily mounted on the vehicle. Indeed, a popular technique for mounting mobile communications antennas is by mounting such antennas on the rear window of the vehicle, and transmitting and receiving the RF energy via a capacitive effect through the window, to the antenna. As is well known, mobile communication antennas operate with transceivers which are capable of the transmission and reception of RF signals using different frequencies, but using the same antenna. Glass-mounted mobile communication antennas of such type are illustrated in U.S. Pat. Nos. 4,266,227; 4,474,353 and 4,839,660.
While the length of mobile cellular communication antennas are relatively short, being about 16 inches in length, making such antennas relatively easy to mount to a vehicle, the high frequency operation imposes other and more critical constraints. For example, in order to provide an omnidirectional electromagnetic pattern of radiation and reception, the mobile communication antennas operate optimally when in a vertical orientation. While this in and of itself does not present a substantial impediment to the design of an economical antenna mount, yet other concerns tend to complicate the design considerations. For instance, the desired location for mounting a mobile communication antenna is to the back window of the vehicle. This places the antenna in a location most removed from the vehicle occupants, on a window that is not movable itself, and out of the line of sight of the vehicle driver. However, because most vehicle models have a different type of rear window design, having a slant from near vertical to 45% or so, a problem arises as to the mounting thereof in a vertical orientation. Accordingly, either many different types of mobile antenna mounts are required, or an adjustable mount is required in order to mount a vertically oriented antenna on the many different types and styles of vehicle windows. U.S. Pat. No. 4,839,660 identified above provides a rigid antenna mount which is effective on a narrow range of rear window slants in order to orient the antenna vertically. On the other hand, U.S. Pat. No. 4,266,227 discloses a window-mounted antenna that is adjustable to accommodate numerous types of windows, and therefore appears to be more universal in use.
While the adjustable antenna mounts identified above appear to be useful for their intended purpose, they are not aesthetically pleasing as substantially all the mounting apparatus and hardware is exposed and thus is visible. While various antenna base hoods and covers might be utilized, such covers would impair the adjustability of the antennas with respect to the mounting bases, or would be unduly complex and thus cost prohibitive. Further, in order to provide a full cover for the antenna mounting base, the cover must be removable to allow the antenna to be adjusted and then fixed to the base, and thus not interfere with such adjustments. Of course, other holes could be provided in a cover to allow screwdrivers or wrenches access to the internal adjusting apparatus, but such a construction would present a compromise in an otherwise aesthetically pleasing smooth and contoured cover.
From the foregoing, it can be seen that a need exists for an antenna having a wide range of adjustments while yet affording an aesthetically pleasing and decorative cover to hide the entire mounting base and adjustment mechanism. Another need exists for a cover with a single opening therein through which the antenna extends, which is snap fittable to the antenna mounting base, and which can be easily installed after final adjustment of the antenna. Another need exists for an antenna mount, and a cover, and an adjustment means for allowing the antenna to be oriented in a position substantially parallel to the surface plane to which the antenna is mounted, while yet utilizing only a relatively small opening in the decorative cover.